Toxic effects of selenium (Se) contamination in freshwaters have been well documented. However, study of Se contamination has focused on lentic and larger order lotic systems, whereas headwater streams have received little scrutiny. In central Appalachia, surface coal mining is a common Se source to headwater streams, thus providing a useful system to investigate Se bioaccumulation in headwater food chains and possible longitudinal patterns in Se concentrations. Toward that end, we assessed Se bioaccumulation in 2 reference and 4 mining-influenced headwater streams. At each stream, we sampled ecosystem media, including streamwater, particulate matter (sediment, biofilm, leaf detritus), benthic macroinvertebrates, salamanders, and fish, every 400 m along 1.2- and 1.6-km reaches. We compared media Se concentrations within and among streams and evaluated longitudinal trends in media Se concentrations. Selenium concentrations in sampled media were higher in mining-influenced streams compared with reference streams. We found the highest Se concentrations in benthic macroinvertebrates; however, salamanders and fish bioaccumulated Se to potentially harmful levels in mining-influenced streams. Only one stream demonstrated dilution of streamwater Se with distance downstream, and few longitudinal patterns in Se bioaccumulation occurred along our study reaches. Collectively, our results provide a field-based assessment of Se bioaccumulation in headwater food chains, from streamwater to fish, and highlight the need for future assessments of Se effects in headwater streams and receiving downstream waters. Environ Toxicol Chem 2020;39:692-704. © 2020 SETAC.

中文翻译：

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硒在营养水平上和在水源流中沿纵向梯度的富集。

淡水中硒（Se）污染的毒性作用已得到充分证明。然而，对硒污染的研究主要集中在透镜状和较大阶数的乳液体系上，而源头水流却很少受到审查。在阿巴拉契亚中部，表层煤开采是上游水源中常见的硒源，因此提供了一个有用的系统来研究上游水食物链中硒的生物富集以及硒浓度的可能纵向模式。为此，我们评估了2种参考水和4种受采矿影响的源头溪流中硒的生物积累。在每条溪流中，我们在1.2公里和1.6公里的范围内每400 m采样生态系统介质，包括溪水，颗粒物（沉积物，生物膜，叶碎屑），底栖大型无脊椎动物，sal和鱼。我们比较了溪流内部和之中的硒浓度，并评估了硒浓度的纵向趋势。与参考流相比，受采矿影响的流中采样介质中的硒浓度更高。我们发现底栖大型无脊椎动物中的硒含量最高。然而，sal和鱼类在受采矿影响的溪流中将硒生物富集至潜在有害水平。在我们的研究范围内，只有一条水流显示出下游的硒水被稀释，且下游距离较远，并且硒生物富集的纵向模式很少。总体而言，我们的结果提供了对从河水到鱼类的上游水食物链中硒生物富集的现场评估，并强调了未来评估上游水源和下游水域中硒影响的必要性。2020年环境毒性化学; 39：692-704。©2020 SETAC。